1. Field of the Invention
The present invention relates to a load connection state detection circuit detecting the connection state of a load such as an external antenna.
2. Description of the Related Art
In the past, in an on-vehicle GPS module, an external antenna receiving a signal from a satellite has been connected to an antenna terminal and used. In the on-vehicle GPS module, an antenna state detection circuit is used that detects whether or not the external antenna is normally connected. Such a technique is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2009-118077.
Such an antenna state detection circuit detects a current flowing through the external antenna connected to the antenna terminal serving as an output terminal, using a detection circuit, and outputs, as a 2-bit output signal, a detected result from a determination circuit to a signal processing circuit. In the signal processing circuit, on the basis of the 2-bit output signal from the antenna state detection circuit, it is determined whether or not the external antenna is adequately connected.
In addition, since, in the on-vehicle GPS module, the temperature change of a usage environment is great, there is made a proposal that a temperature compensation circuit used for correcting a circuit characteristic due to a temperature change is used. Such a technique is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 11-155229.
Such a temperature compensation circuit includes a transistor and a diode whose anode is connected to the base of the transistor and whose cathode is grounded. Such a temperature compensation circuit, since a diode is used where the temperature characteristic of a forward voltage is closely related to the temperature characteristic of the base voltage of the transistor, it may be possible to reduce a difference in a voltage applied to the base of the transistor even if the temperature change has occurred. Accordingly, since it may be possible to reduce a change in a current value between the emitter and the collector of the transistor due to the temperature change, it may be possible to realize a temperature compensation function.